Winch

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Modern self-tailing winch on a sailing boat. Here, the line winched is a jib or spinnaker sheet which runs from the sail (upper left, not shown) to a block (lower right,not shown) and from there to the lower part of the winch. The handle is detachable to facilitate handling of the line.

A winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise adjust the "tension" of a rope or wire rope (also called "cable" or "wire cable"). In its simplest form it consists of a spool and attached hand crank. In larger forms, winches stand at the heart of machines as diverse as tow trucks, steam shovels and elevators. The spool can also be called the winch drum. More elaborate designs have gear assemblies and can be powered by electric, hydraulic, pneumatic or internal combustion drives. Some may include a solenoid brake and/or a mechanical brake or ratchet and pawl device that prevents it from unwinding unless the pawl is retracted.

Applications

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Anchor winch of the polar research vessel Polarstern

Besides industrial applications (e.g. in cranes), winches are used for towing cars, boats, or gliders. There are several winches on almost every boat or ship where they are used to pull anchor or mooring lines, halyards, and sheets.

The two most common types of winches are planetary and worm gear. A planetary winch usually is designed for light duty use, and have a fairly fast line speed. These are usually seen on the front of pick up trucks, Jeeps, etc. A worm gear winch usually has a rather slow line pull, but is designed to have a slow and steady pull that will hold the load that is being pulled. These types of winches are usually seen on car hauling trailers, and larger work trucks.

The rope is usually stored on the winch, but a similar machine that does not store the rope is called a capstan. When trimming a line on a sailboat, the crew member turns the winch handle with one hand, while tailing (pulling on the loose tail end) with the other to maintain tension on the turns. Some winches have a "stripper" or cleat to maintain tension. These are known as "self-tailing" winches.

Winches are frequently used as elements of backstage mechanics to move scenery in large theatrical productions. Winches are often embedded in the stage floor and used to move large set pieces on and off.

Winches have recently been fabricated specifically for water and snow sports (e.g. wakeboarding, wakeskating, snowboarding, etc.). This new generation of winches are designed to pull riders swiftly across a body of water or snow by simulating a riding experience that is normally supplied by a boat, wave runner, or snow mobile.

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Example of winch designed for wakeboarding. These winches consist of a small four-cycle gasoline engine, clutch, and spool all housed inside of a steel frame. A rider is towed rapidly toward the winch as the rope winds around the spool.

Tirfors

Tirfors also commonly known as griphoists are winches that instead of using spools to move rope or wire through the winch use self-gripping jaws. Powered by moving a handle back and forth they allow one person to move objects several tons in weight.

Snubbing winch

This is a vertical spool with a ratchet mechanism similar to a conventional winch, but with no crank handle or other form of drive. The line is wrapped around the spool and can be tightened and reeled in by pulling the tail line, the winch takes the load once the pull is stopped with little operator tension needed to hold it. They also allow controlled release of the tension by the operator using the friction of the line around the ratcheted spool. They are used on small sailing boats and dingies to control sheets and other lines, and in larger applications to supplement and relieve tension on the primary winch mechanisms.

Wakeskate winch

Wakeskate winching, which is the popular term today, is a growing hobby for many watersports enthusiasts. It consists of an engine, spool, rope, handle, frame, and some sort of simple transmission. The person being towed walks (or swims) away from the winch and pulls out all of the rope. When the winch is engaged, it pulls the boarder usually between 15 to 25 miles per hour (24 to 40 km/h). Winches are popular for people wanting to board on ponds and lakes, or just don't have a boat. Also, the winch can either be mounted on the trailer hitch of a vehicle, set into the ground by stakes, or tied to a tree. These are the most popular ways to secure the winch, but are still dangerous.

History

The earliest literary reference to a winch can be found in the account of Herodotus of Halicarnassus on the Persian Wars (Histories 7.36), where he describes how wooden winches were used to tighten the cables for a pontoon bridge across the Hellespont in 480 B.C. Winches may have been employed even earlier in Assyria. By the 4th century BC, winch and pulley hoists were regarded by Aristotle as common for architectural use (Mech. 18; 853b10-13).

See also

• Capstan equation
• Hoist (device)
• Hoist (mining)
• Pulley
• Steam donkey

External links

• Article about boat winches